 In this video, with our three planes of MRI images, we're going to take a look at a couple more important structures of the brain. Over this side, we've taken away the cerebrum to leave just the thalamus and the brainstem. Let's begin at the thalamus. It has simple geometry in our 3D model. Between its two major chunks, there is this smaller connecting portion. This is called the interthalamic adhesion. This sagittal image here is in the midline of the brain, as if an image has been taken of this plane. This little part there, that's the interthalamic adhesion, which is here on the coronal plane. If I move the sagittal plane slightly to the left, and let me show you what I've done on my 3D model here, slightly to the left there, you can see more of the thalamus just here. Now all around this interthalamic adhesion is fluid, best appreciated in the sagittal plane. And that's the third ventricle. It's filled with cerebrospinal fluid. Just above the third ventricle lies this line of white matter here. This is called the fornix. And there it is on the coronal plane. Keep your eye on the coronal plane now as I scan through it. Here it's a single line, but as I proceed posteriorly, it splits into two separates like that. So this is best appreciated in three dimensions. So there's the thalamus again, and here's the fornix arching over the top of it. Appropriately fornix is Latin for arch. Its legs then curl around either side like so. Now there's another even larger arch of white matter, which is called the corpus collosum. Its orientation is much more straightforward than its little brothers. And there it is on our 3D model. If we observe its path in the coronal plane, it blends in to the white matter either side of it, which is appropriate because it's one of the main pathways in the brain for neurons that are crossing over from one side of the brain to the other. There's the fornix just beneath it. And these dark areas here are the lateral ventricles. Now running between the corpus collosum and the fornix and separating the two lateral ventricles is the septum pollucidum. Back to our sagittal image. So there's the midline. There's the fornix. There's the corpus collosum. And there's the septum pollucidum between them. Over to our model again. We'll bring that in now. Imagine the lateral ventricles separated by this thin sheet of membrane called the septum pollucidum. And the third ventricle is hidden in here between the two chunks of the thalamus. Now let's talk about the hypothalamus, which I always found terribly confusing in first year. But it's really so simple. It's just two lobes hanging off each side of the thalamus, joining together to form the pituitary gland. The harder part is finding it on our MRI. So we'll find the pituitary gland first in the transverse plane and then we'll work backward from that. Now moving down through the transverse plane. Can you see that X shape there? That is the optic chiasm. And sitting just beneath the optic chiasm is the pituitary gland. That should be it. Just there. And if we look over at our sagittal image, there it is. Now we look for the connection between that and the thalamus, which is the hypothalamus. We move just a couple of slices over. There it is there. It's quite faint. But the hypothalamus, which connects the pituitary gland to the thalamus, which sits underneath the phonics, which is connected to the corpus callosum by the septum pollucidum. Let's go through that again on our 3D model. There's the pituitary gland, connected to the thalamus by the hypothalamus. There's the phonics arching over the thalamus. There's the septum pollucidum attaching the phonics to the corpus callosum. You'll have to imagine the lateral ventricles forming either side of that. And if we remove the phonics now, we can see the third ventricle in the space that surrounds the interthalamic adhesion. That's it for this video. Hit like if you found it useful, and we will see you next time.